1. Field of the Invention
The present invention relates to a quick connector which is used when a flexible tube formed of a resin, rubber, or the like is connected to a mating pipe. More specifically, the invention relates to a quick connector for connecting a flexible tube used for transporting fuel to a mating pipe.
2. Description of the Related Art
Conventionally, as a connector for connecting a flexible tube formed of a resin, rubber, or the like to a mating pipe, to transport fuel, for example, to transport fuel in a fuel tank to an engine side, the following quick connector is used. Namely, this quick connector is comprised of (a) a connector body which is formed in a tubular shape as a whole and has on its one axial side a socket-like retainer holding portion for insertion of the mating pipe therein and on its other side a tube connecting portion which is press fitted into a tube; (b) a retainer which is held in an axially fixed state by the retainer holding portion and serves as a detent for the mating pipe by axially engaging an engageable portion of an outer peripheral surface of the mating pipe over which an engaging portion on an inner peripheral side has been fitted; and (c) a seal member which is fitted in the interior of the connector body, i.e., in an innermost part located on the tube connecting portion side away from the retainer holding portion, and serves as a seal by coming into contact with an outer peripheral surface of the inserted mating pipe. Further, a plurality of annular projections serving as detents for the tube by biting into an inner surface of the tube are formed in the tube connecting portion in such a way as to be axially spaced apart from each other.
For example, JP-A-7-71673 discloses a quick connector of this type.
FIG. 8 specifically shows an example thereof.
In FIG. 8, reference numeral 200 denotes a quick connector for connecting a tube shown in FIGS. 9A and 9B to a mating pipe 204, and the quick connector 200 has a connector body 206 (made of a resin in this case).
The connector body 206 is formed in a tubular shape as a whole and has on its one axial side a socket-like retainer holding portion 208 for insertion of the mating pipe 204 therein and on its other side a tube connecting portion 210 which is press fitted into the tube 202 (shown in Figures 9A and 9B), a housing 212 being provided midway there between.
In the connector body 206, an O-ring 214 and a bush 216 are fitted in an innermost part located on the tube connecting portion 210 side away from the retainer holding portion 208, specifically inside the housing 212. The O-ring 214 and the bush 216 are adapted to come into contact with and seal an outer peripheral surface of the inserted mating pipe 204.
A window portion 218 having the shape of an opening is provided in the retainer holding portion 208. A front end portion (on the left end side in the drawing) of a frame portion on an outer peripheral side of the window portion 218 is formed as an engageable portion 220 for engaging a groove-like engaging portion 224 in a retainer 222 which will be described later.
The retainer 222 (made of a resin in this case) is a member which is formed separately from the connector body 206 and is held by the retainer holding portion 208, and the retainer 222 is resiliently deformable in the radial direction.
This retainer 222 engages the engageable portion 220 of the retainer holding portion 208 at the groove-like engaging portion 224 on the outer peripheral side, and is held in an axially fixed state by the retainer holding portion 208 as a result of their engaging action.
The retainer 222 has an engaging portion 226 on the inner peripheral side constituted by an engaging pawl, and this engaging portion 226 is adapted to axially engage an engageable portion 228 constituted by an annular projection on the outer peripheral surface of the mating pipe 204 so as to prevent the mating pipe 204 inserted in the connector body 206 from coming off.
This retainer 222 further has an inner peripheral cam surface 230 and an outer peripheral cam surface 232 which are provided on its inner peripheral surface and outer peripheral surface and which serve as engaging guides.
The inner peripheral cam surface 230 and the outer peripheral cam surface 232 act as follows.
Namely, when the mating pipe 204 is axially inserted with the retainer 222 held by the retainer holding portion 208, the inner peripheral cam surface 230 abuts against the engageable portion 228 of the mating pipe 204 and serves as a guide for the insertion of the engageable portion 228. At the same time, the inner peripheral cam surface 230 resiliently expands the retainer 222 by means of its cam action.
When the engageable portion 228 passes the engaging portion 226, the retainer 222 returns to its state of reduced diameter and causes the engaging portion 226 to axially engage the engageable portion 228 of the mating pipe 204.
At this stage, the mating pipe 204 is prevented from coming off the connector body 206.
At the time of insertion of the mating pipe 204, the retainer 222 can be attached in advance to the mating pipe 204 side. In this case, when the mating pipe 204 is inserted into the connector body 206, the outer peripheral cam surface 232 of the retainer 222 abuts against the engageable portion 220 of the retainer holding portion 208 and resiliently deforms the retainer 222 in the diameter-reducing direction.
When the engaging portion 224 on the outer peripheral side reaches the engageable portion 220 of the retainer holding portion 208, the retainer 222 undergoes expansion in its diameter, and the engaging portion 224 and the engageable portion 220 form an axially engaged state.
The aforementioned tube connecting portion 210 has a small diameter with respect to the housing 212. A wall 234 orthogonally rises radially outwardly from its joint. This wall 234 serves to define a fitting length of the tube 202 by causing a distal end face of the tube 202 to abut against it.
This tube connecting portion 210 is provided with a plurality of annular projections 238-1, 238-2, and 238-3 in such a manner as to be axially spaced apart from each other.
These annular projections 238-1, 238-2, and 238-3 bite into the inner surface of the tube 202 to serve as detents, and their tips are shaped in the form of acute-angled saw teeth in terms of their cross sections.
Portions between these annular projections 238-1, 238-2, and 238-3 of the tube connecting portion 210 are formed as flat surfaces 240-1 and 240-2 which are parallel to the axial direction.
In addition, a portion between the joint of the tube connecting portion 210 and the annular projection 238-3 which is the farthest one and closest to that joint is formed as a flat surface 240-3 which is similarly parallel to the axial direction. In addition, a portion extending more on the distal end side than the most distal end-side annular projection 238-1 is also formed as a flat surface 240-4 which is similarly parallel to the axial direction.
Here, the respective flat surfaces 240-1, 240-2, 240-3, and 242-4 have the same diameter.
The reason the flat surfaces 240-1 and 240-2 are formed between adjacent ones of the annular projections 238-1, 238-2, and 238-3, and the flat surfaces 240-4 and 240-3 similarly of the same diameter are formed in the front end portion and the rear end portion is as follows: When such a tube connecting portion 210 is press fitted into and connected to the tube 202, the tube connecting portion 210 and the tube 202 can be brought satisfactorily into a state of close contact, and hence the coming-off force of the tube 202 can be increased.
Specifically, as for the tube 202 which is fitted over the tube connecting portion 210, its inner surface is deflected in such a manner as to be brought substantially into close contact with the flat surfaces 240-1, 240-2, 240-3, and 240-4, and the depth of the biting of the annular projections 238-1, 238-2, and 238-3 into the inner surface of the tube 202 becomes deep. Hence, the effect of preventing the coming off of the tube 202 is enhanced.
Furthermore, the inner surface of the tube 202 is brought substantially into close contact with the flat surfaces 240-1, 240-2, 240-3, and 240-4, and as the area of contact between the tube connecting portion 210 and the inner surface of the tube 202 increases, the coming-off preventing effect is enhanced.
Incidentally, reference numeral 242 denotes an O-ring groove having a cross-sectionally rectangular shape. As shown in FIGS. 9A and 9B, an O-ring 246 for providing a seal with respect to the tube 202 is adapted to be fitted therein.
As for this quick connector 200, as shown in FIG. 9B by merely pressing fitting the tube connecting portion 210 into the tube 202 and inserting the mating pipe 204 into the connector body 206 from the opposite side as shown in FIG. 8, the tube 202 and the mating pipe 204 can simply be set in a connected state.
As for this quick connector 200, as shown in FIG. 9B, by merely pressing fitting the tube connecting portion 210 into the tube 202 and inserting the mating pipe 204 into the connector body 206 from the opposite side, the tube 202 and the mating pipe 204 can simply be set in a connected state.
With this quick connector 200, there is a problem in that a stress is likely to concentrate in the root portion of the tube connecting portion 210 having a small diameter, and this portion becomes a weak point portion in terms of strength.
The connector body 206 and the tube connecting portion 210 become large or slender depending on the diameter of the tube 202 to be connected. In either case, this problem occurs in common. However, particularly when the diameter of the tube connecting portion 210 becomes small in correspondence with the diameter of the tube 202, a large load acts in that root portion in a concentrated manner. Hence, there is a problem in that in cases such as where a bending force or the like is applied through the tube 202 at the time of connection of the tube 202 or after the connection, there is a possibility of the tube connecting portion 210 being broken at that root portion. Especially, this problem likely occurs in the case where the inner diameter of the tube 202 is 5 mm or less.
Also, when the entire length of the tube connecting portion 210 is long relative to the inner diameter of the tube 202, more specifically, when the value derived by dividing the entire length of the tube connecting portion 210 with the inner diameter of the tube 202 is 5 or more, particularly when the value is 6 or more, the same problem likely occurs.
U.S. Pat. No. 6,129,393 discloses a quick connector in which the cross-sectional shape of the joint of the tube connecting portion 210 is a round shape (circular arc shape).